The BumpMap
Method
The second method,
Deformation->BumpMap in the Model module, uses a more sophisticated
and challenging technique to determine the height of each
polygon in a mesh.
To start, you
paint a 2D Image map, using the Softimage Paint program, Adobe
Photoshop, or a similar image tool. The file should be a color
image, where darker tones represent lower areas of geometry
and lighter tones represent higher areas (see Figure 7.53).
By painting a pattern of changing color values, you can precisely
control the topography that is constructed.
Figure
7.53 A good starting image, with different
hues indicating changes in topography.
The BumpMap tool
can use changes in hue between the red, green, and blue channels
to change the topography generated, as well as changes in
the alpha channel. So feel free to paint different things
in the R, G, B, and A channels to make a more complex landscape.
Convert the image
to a Softimage .pic file if you use a separate tool, or just
save it if you use the Paint program within Softimage 3D.
Next create a
starting mesh object. The target mesh object should have enough
detail to deform cleanly into the terrain shape, and can be
either a polygon mesh, or a patch, including NURBS.
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The
more detail the starting mesh has, the better looking
the results will be. Particularly nice landscapes
can be made by creating a Cubic NURBS grid with
15 cells in U and V, and moving groups of points
manually to set the major features of the landscape
before applying the BumpMap effect to fill in minor
detail (see Figure 7.54).
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Figure
7.54 A good starting mesh, with points raised
to create major landmarks.
Invoke the Deformation->BumpMap
command and set the parameters as you wish in the dialog box
(see Figure 7.55).
Figure
7.55 The BumpMap dialog box.
Start by directing
the tool to the picture file you want to use with the Browser
button. Then pick the projection plane for the image to be
mapped onto the surface. If the mesh is in the default XZ
plane, visible from the top in the Top view window, use the
ZX projection. The UV projection doesn't seem to work, so
avoid it.
Figure
7.56 A greyscale displacement map painted
to create an island for the Cyan CD-ROM game Riven. Printed
courtesy of Cyan Inc. Copyright 1997.
The Height of
Bumps control sets the overall amount of deformation applied
by the effect in Softimage units. The contribution to that
amount for each channel of the image (red, green, blue, and
alpha) can be adjusted by setting the Channel factors from
0.0 to 1.0, where 0.0 is no influence at all and 1.0 is all
the influence possible for that channel. (Setting the numbers
higher than 1 has no effect.)
The Filter Type
determines which filter is applied to smooth the map between
vertices that fall between pixels, and Gaussian should yield
more accurate results.
Figure
7.57 The island displacement map with the map
of the island superimposed on it showing features. Printed
courtesy of Cyan Inc. Copyright 1997.
You can choose
to deform all the vertices on the mesh or only the tagged
ones, and the vertices can be moved in a positive Y direction,
or along the average of the neighboring normals. While moving
along the normals yields more accurate and interesting results
if you deform the surface manually before applying the effect,
you will need less main bump height.
Click the Ok
button to close the BumpMap dialog, and then pick the mesh
to complete the effect (see Figure 7.54).
